Personally, I would have thought the chances of you making money in the first year or two, are pretty slim, so I would avoid spread betting - as spread bets have a wide spread to cover their costs and extra gaming revenue. And all that will happen is, you may end up losing money on what could have been a winning position due to the spread.
If you're going to trade indices use CFD's. If you're going to trade individual equities use a broker. Remember with the ammount of comm you pay.. you get what you pay for.
When and If you start to make money, and the capital gains tax becomes an issue- then look at SB.
Wayno